14A new method, based on Singular Value Decomposition (SVD) and QR factorization, has been 15 developed and applied to the analysis of F-18 flutter flight-test data. The method is capable of 16 identifying the frequency and damping of the critical aircraft modes, those responsible for the flutter 17 phenomenon. The procedure relies on the capability of SVD for the analysis, modelling and 18 prediction of data series with periodic features and also on its power to identify matrix rank. The 19 analysis of simulated and real flutter flight test data demonstrates the effectiveness, robustness, 20 noise-immunity and the capability for automation of the method proposed under specific conditions. 21 22
Continuing with the analysis performed for the one-dimensional axially loaded bar problem, a beam in bending is analysed to understand the influence of the characteristic parameters that have any influence in the solution of this problem using the element-free Galerkin method (EFGM), one of the most popular meshless methods. Both accuracy and time cost are considered as the evaluation functions to perform such an analysis. Both functions provide a reasonable idea to consider EFGM as an adequate method to solve the problem considered in this article. As in a one-dimensional axially loaded bar problem, the parameters to be considered will be those that affect the solution: number of nodes in which the domain is modelled, the nodes scatter, the order of the polynomial base to generate shape functions, the order of the quadrature to solve integrals, and the support radius. Besides, as in a one-dimensional axially loaded problem, some cases with different loading and stiffness conditions are considered. However, in this analysis a generalized moving least squares method is used to create shape functions instead of the moving least squares.
This paper analyses the applicability of the Statistical Energy Analysis (SEA) for detecting incipient damages in a typical spacecraft structure, as a stiffened panel. The damage on attachment element is investigated by analyzing its influence on the system characteristics. Because of incipient damage affects mainly on highest modes, rather than on lowest, the coupling loss factor between sub-elements can be used to detect and localize the damage.
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